It's probably safe to say Invoice2go's smartwatch app is in the first category, or at least Apple thinks so.

Around six months ago, the Australian company behind the accounting platform was invited to be part of the Apple Watch program. It followed an injection of A$35 million into the company in 2014 by Silicon Valley investment heavyweights.

"[Apple] saw a lot of opportunity with our app, because they wanted small business owners to realise that just like the iPhone changed things up, the watch could also," the company's founder Chris Strode told Mashable Australia.

Invoice2go's smartwatch app serves people like carpenters, electricians and freelance designers, who can check in and out of a job, track time and generate an invoice right from their wrist. The app can even use geo-sensing to remind you to track time when you arrive at a job site.

Here five tips for building a successful Apple Watch app from someone in the know: Chris Strode.

1. Keep user actions simple

The way a user interacts with the smartwatch app should be kept to an efficient minimum.

"I think what Apple liked about [our watch app] was that we kept it to really small interactions," Strode said. "Things that would take between one and three seconds." Tracking time on the Invoice2go app using simple choices — yes / no or start / stop actions, for example — suited the smartwatch format perfectly.

In fact, the concept of binary actions came highly recommended by Apple. "That's how they want people to interact with the watch," Strode said. "We really took that to heart and designing around that concept is what helped us to get to WWDC."

Founder of Invoice2go, Chris Strode.

Image: Invoice2go

2. Don't just transfer a smartphone app to the Apple Watch

The biggest mistake you could make is to try and replicate the performance of an existing tablet or smartphone app on the smartwatch, Strode said. Instead, build a product that really works from the wrist.

Designers will find components of their app that make sense on a watch, he added. Notifications, for example, become really powerful when you don't have to reach into your pocket for your smartphone.

3. Choose the right look

Having a distinctive colour palate is important. The black background of the smartwatch means you've got to get the colours right, according to Strode. "We've really gone back to flourescent colours," he said. "They're back in because of that black background."

He also recommends following Apple's lead on the visual qualities they've given to their own smartwatch apps. The brightness of the face, the way the screens are laid out and even how you handle animation are all factors to consider and that are worth taking the time to get right.

The Invoice2go smartwatch app.

Image: Invoice2go

4. Make a solid smartphone app

One important consideration many people forget is that the Apple Watch is a companion, Strode said. It's just not going to work without your iPhone.

For this reason, a great deal of development work needs to go into developing a high-functioning smartphone app that pairs seamlessly with the Apple Watch app. "You're essentially building on top of it," he added.

5. Simplicity and detail

For Strode, building Invoice2go's Apple Watch app was above all a process of creative elimination. "You have to think a lot harder about what the most important element is on the screen and what it is you're trying to do," he said. "You have to strip away a lot of stuff to get to the core."

Designers should make sure they treat development as carefully on the device as they would designing for a larger screen. "Even though it's smaller real estate, it still takes just as much effort," he said. In fact, the Invoice2go team found the smaller the screen, the harder it was to get right.

Although Strode admires the Uber smartwatch app, as well as Apple's training apps for tracking health data, he feels the platform is just beginning to mature. Even Apple's own APIs are still evolving, he pointed out. Designing for the Apple Watch will change as apps are able to access more of the smartwatch's core functionality

In the meantime, he recommends designers dig down into ideas that will be most effective on this new type of device. "Then go at it, full steam ahead."

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